The invention relates to a lock for the loading and/or discharging of, in particular, not easily flowing, adhering bulk materials into or out of a pressurized or vacuum chamber through a discharge opening of a discharge housing.
The discharge of bulk materials which are processed, e.g. mixed or kneaded, in pressurized or vacuum chambers takes place, for example, by means of so-called star feeder locks. In these star feeder locks, sectorial pockets are formed into which the bulk material drops as a result of its gravitational force. As soon as one pocket is filled, the star feeder is rotated further so that the next pocket can be filled while a pocket which has already been filled is emptied.
These vacuum star feeders entail problems, above all because, on the one hand, the pockets are not completely emptied. On the other hand, the pressure or the vacuum prevailing in the operating chamber must be sealed off by the star feeder, which is only effected unsatisfactorily. Thirdly, a volume of gas corresponding to the star feeder is also fed into the apparatus.
Furthermore, an arrangement is known, in which the operating chamber is adjoined by an intermediate container which is closed off, on the one hand, in relation to the chamber by means of a valve and, on the other hand, in relation to the actual discharge by means of a further valve. Here, too, the problem essentially lies in the fact that the product only passes through the valves and the intermediate container as a result of its own gravitational force. Furthermore, the valves must perform their sealing function against the vacuum or the pressure inside the product flow. It is true that special gates have been developed for this purpose, but these are complex and leave much to be desired regarding tightness. Moreover, prior to opening the corresponding gates, the intermediate container must be evacuated or aerated in order not to affect the pressurized or vacuum chamber. This requires idle times and makes the process more expensive.
Discharge of the abovementioned bulk materials is also possible by means of a screw conveyor, but the problems regarding sealing are even greater in this case.
Accordingly, it is the principle object of the present invention to develop a lock of the abovementioned type which has no effect on the pressure or the vacuum in the operating chamber, which discharges the product carefully, is of simple construction and operates with little wear.